1. Field of the Invention
This invention relates generally to improvements in the field of thrust reversers for turbofan aircraft jet engines and more particularly, but not by way of limitation, to an improved pivoting door type thrust reverser system having a deployable cold air flow deflector.
2. Description of the Prior Art
Aircraft turbojet engines of the turbofan type are well known in the art and typically comprise a primary exhaust gas nozzle to exhaust the high temperature, high pressure gas emanating from the core engine. Turbofan type engines also include a secondary duct concentrically located about the primary exhaust gas duct so as to define an annular space therebetween. Large diameter turbofan engines direct a cold flow of air through this annular space to increase the performance characteristics of the aircraft engine.
Thrust reversers are also well known in the art and usually comprise one or more thrust reverser doors serving to redirect the flow of gases from their normal downstream direction to a direction which has a component in the forward direction. In civilian aircraft application, where such engines have a relatively high bypass ratio, the ratio of the quantity of air passing through the secondary or cold flow annular space to the quantity of gases passing through the primary duct, the thrust reverser may be applied solely to the secondary or cold flow duct. In that instance the thrust reverser door and the actuating mechanism may be integrated into the wall of the secondary duct.
In such known systems, the thrust reversing doors are displaceable between a retracted position, in which they form a part of the outer wall of the secondary duct and do not imped the air flow through the annular space and an extended position in which the doors will block at least a portion of the air flowing through the annular or bypass duct and re-direct it in a direction having a forward acting component.
Thrust reverser doors for pivoting door type thrust reverser systems may assume various shapes. In the instance of a flap-type door, a deflector will usually be attached to the upstream edge of the door so as to redirect the reversed cold air flow to have a more forward acting component. In order to provide for adequate performance of a thrust reverser using this flap type door, this deflector must have a minimum length extending inwardly from the inner surface of the thrust reverser door. In order to accommodate this length when the door is in a stowed or forward thrust position, the inner wall of the secondary or bypass duct usually is located adjacent to the end of the deflector to prevent the deflector from extending into the annular air space and disrupting the cold air flow.
However, in order to maximize the performance of the thrust reverser, the inner surface of the door usually defines a cavity or a concave portion. When the door is in its stowed position, this concavity is located downstream of the deflector. The presence of this concavity when the thrust reverser door is in the retracted position produces aerodynamic losses in the cold air flow passing through the bypass duct, thereby reducing the efficiency of the engine when in the normal thrust mode.
Thus, a need has long existed in the prior art for a cost efficient, improved pivoting door thrust reverser system that is simple in operation and which overcomes the difficulties involving in trying to overcome the concavity problem associated with a pivoting reverser door having a fixed deflector.
The following patents, while of interest in the general field to which the invention pertains, do not disclose the particular aspects of the invention that are of significant interest.
Efforts to overcome these shortcomings generally involve three types of approaches. One type, as seen in U.S. Pat. No. 4,894,985, is to employ a movable deflector that is mounted on the thrust reversing door and which is connected to a complicated linkage arrangement driven by a bell crank mounted on the door that is initially actuated by a connection to the extended end of an actuator. Another type is that seen in U.S. Pat. Nos. 4,916,895; 4,922,712, and 5,003,770, which illustrate movable panels carried by the thrust reverser door that normally are flush with an inner surface of the duct and which are retracted against or into the thrust reverser door as it is deployed to expose the fixed defector means.
A third type is seen in U.S. Pat. Nos. 4,858,430; 5,716,025, an 4,956,466, which show various schemes of attempting to extend downstream the upstream portion of the lateral opening to receive the door for the purpose of alleviating the concavity problem while still maintaining the full extension of a fixed deflector on the thrust reverser door. Such extensions involve perforated extensions, movable extensions and extensions secured to the actuator body.
It is a general object of the invention to provide an improved pivoting door type thrust reverser which provides a bypass fan duct having an outer flow surface that is smooth and which has no concavity or protrusion associated with the thrust reverser door.
It is another general object of the invention to provide a pivoting thrust reverser door that is straight forward in design and which is simple in order to enhance reliability and to provide low cost.
It is yet another object of the invention to provide a deployable kicker plate door arrangement which does not require internally mounted mechanisms within the door.
It is a specific object of the invention to provide a latch arrangement for the deployable kicker plate arrangement which allows for easy rigging during assembly as well as ease of access and maintenance.
The foregoing has outlined some of the more pertinent objects of the invention. These objects should be construed to be merely illustrative of some of the more prominent features and applications of the intended invention. Many other beneficial results can be attained by applying the disclosed invention in a different manner or by modifying the invention within the scope of the disclosure. Accordingly, other objects and a fuller understanding of the invention may be had by referring to the summary of the invention and the detailed description of the preferred embodiment in addition to the scope of the invention defined by the claims taken in conjunction with the accompanying drawings.